Here's a collection of vero (stripboard) and tagboard guitar and bass effect layouts that we have put together covering many classic and popular effects in growing numbers. Many of these have been posted on freestompboxes.org, so check that site out for great discussions on building your own effect pedals. Enjoy the builds and please also visit us on Facebook and Twitter

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Tuesday, 27 September 2016

Electro Harmonix Octave Multiplexer

Here is a layout for a classic pedal.
I've drawn 2 versions: Vintage and Modern.
There are 2 layouts for the Vintage: with and without output boost.
I've added a boost to the Modern layout to avoid volume loss.
You can find the original FSB thread here.
16/01/2017 Layout updated! I've changed the vintage layouts because there were some errors in the schematic.
Thanks to Barcley for pointing out the corrections that I needed to make!

58 comments:

Hi Alex. Thanks for some great layout once again. I build the modern one but I have some problem, I can't make it works. I tried to check my build but I wasn't able to find errors (it's maybe on my side but I didn't find). I also tried to change IC's and trannies in case of faulty one but nothing better. Any help would be very appreciate.

Hi Thomas.Did you compare the layout to the schematic?I think it's ok but I won't be able to check again until Monday.I'm not able to see all the cuts from the pictures but I assume you already double checked everything.From your circuit picture, I think both transistors are reversed. Have you checked the pinout?

Thanks for the comment. I checked cut and pinout.. I placed the tranies by respecting letters but I tried to reverse them without success.I tried to look at the schematic also but I don't hAve the knowledge to understand. I just know building.

Hi Thomas!Had a look again and there were a couple of mistakes:from the 2n5457 Ground there is a 1M resistor that should go to ground, one row below (it goes to Vref on the previous layout).The 100n cap at the bottom right corner should be removed.I've already changed the layout.

OK, thank you I will test that and keep you updated. You were right on my pics trannies were reversed. I remove them to test them and put them back quickly (and badly to make the test).Not sure to have the time tonight but tomorrow it should be good.

It sounds very nice. I don't really know the original but from what I heard on the web it's close, maybe a bit more artefact (not on every setting).The boost help a lot, you can even have a volume boost so it's perfect.Thanks again for your work and the help you gave me.

IMO it's a bit misleading to talk about "volume loss". I own the reissue and modern XO version, plus a former bandmate has a vintage specimen. None of those have volume drop issues. Like johnk says in the FSB thread: "I found that it could use a bit more output so I added a Jfet boost to the output with a volume control". Boost afterwards isn't a bad thing and adds to usability. But nevertheless, the original is an octave pedal and always performs at unity level, no matter the source instrument. Adding a JFET stage and volume control are extra features that are not essential.+m

Hello Ozzy,ICLM324 parallel with the IC4013 has a lot of mistakes to the original shematics.1. The diodes D1 and D3 should tourn poles2.The connection betwen 2-13 should be discontinued 3.Make to bridge 1-13 pin4.Bridge 10-6 should be discontinued5.Make bridge 10-7 pinEverything else is fine althoug there is a slight disagreement with some components.

Hi Barcley.There are no mistakes.The layout is identical to the boosted one and that's been verified.This is the schematic:http://www.freestompboxes.org/download/file.php?id=27474&mode=viewLM324 is a quad op-amp and pins numbering can be swapped around to suit the layout.Please, next time, if you think there are any mistakes point them out to the person that has drawn the layout.That way we can explain all the possible changes we have made or correct the mistakes if there any (of course is more than possible, we are human).That way we'll avoid confusing people.

Hello Alex,I do not want to convince youBut you're wrongIt is possible that you have misunderstoodI guarantee what you publishAll that I announce the first try.So this scheme octave Multiplexer(Vintage70`s)If you want to see for yourself, so try.My works perfectly and I am very satisfied.Oh yes, and I replaced the FET transistor with a J 201And finally, I do not intend to confuse people but to help advice, thank you.

Hello Alex,I do not want to convince youBut you're wrongIt is possible that you have misunderstoodI guarantee what you publishAll that I announce the first try.So this scheme octave Multiplexer(Vintage70`s)If you want to see for yourself, so try.My works perfectly and I am very satisfied.Oh yes, and I replaced the FET transistor with a J 201And finally, I do not intend to confuse people but to help advice, thank you.

Now I am really confused...Alex, please, could you check my board if you can see anything suspicious? Thanks a lot again!https://drive.google.com/open?id=0B8HeRqgTRGTCeUYyblVRSkk5RUEhttps://drive.google.com/open?id=0B8HeRqgTRGTCcGRjM1hfTzVEYW8https://drive.google.com/open?id=0B8HeRqgTRGTCbTk0bFJJblpmMnM

Hey Barcley!Sorry but I didn't understand what you've meant with"I guarantee what you publishAll that I announce the first try.So this scheme octave Multiplexer(Vintage70`s)".Of course I could be wrong and any help is more than appreciated.What I was saying is that the vintage layout (with or without the boost are pretty much the same) has already been verified by Gavin and I trust his judgement.And I wasn't sure the schematic was correct until that moment.I have to relay on other people verifying them, I can't build all the layouts I draw.If you write a post addressed to Ozzy where you say that half layout is wrong and that there are parts missing people are gonna get confused because the layout had already been verified.And that doesn't mean you are wrong!If you address a post with your suggestions to "me" first, I would be more than happy to check them because none of us like to keep wrong layouts on the blog.That's what I was saying.Which schematic did you compare the layout to?This:http://www.freestompboxes.org/download/file.php?id=27474&mode=viewor this:http://www.freestompboxes.org/download/file.php?id=26589&mode=view ?

Hi AlexI did not say that half of the schedule is not true.I'm pinpoint what is not good.I'm staying in their assertion.Maybe you did not understand me, my bad English is the reason, I'm sure.http://s514.photobucket.com/user/midnight_liberation/media/EHOctave_Multiplexer_1975.gif.htmlThe first data schema for the vintage version is 99% of the match.Exscept apart from what I said.Check and see.I have made vintage version as the blog (not good).With my correction works perfectly.I have not invented anything new, I just applied logic.When something is not good, find the problem.Thank you for writing,I'm here if you need to clarify anything.

Ok. Now I understand.I thought you've made your changes based on the schematic from FSB!Never seen the one you've used!What I don't understand is how the layout have been verified.Hey Gavin! Is the layout you've built working properly? (Apart from the tracking. I think the tracking is not as good as the newer versions anyway)

Mine never sounded what i expected so i think its in the debug pile at the moment. The sound and tracking were weird in not a good way, if i remember correctly. What exactly is the problem? Maybe i can try a fix.

Hi Gavin.I've thought it was working.Barcley has found a different "corrected" schematic:http://s514.photobucket.com/user/midnight_liberation/media/EHOctave_Multiplexer_1975.gif.htmlTry his suggested changes:1. The diodes D1 and D3 should tourn poles2.The connection betwen 2-13 should be discontinued3.Make to bridge 1-13 pin4.Bridge 10-6 should be discontinued5.Make bridge 10-7 pin

http://topopiccione.atspace.com/pjimages/EHOctaveMultiplexer.sch.gifHere is a link with two JRC4558 instead LM324.Link in the previous message with two LM324.I hope that now everything is clear.Greeting.

Ok, applied the changes mentioned by Barclay and its sounds much more like it should. Before it sounded like two signals out of phase, but i just wasn't sure if it was correct or not. Now its definitely correct. Cheers Alex and especially Barclay.

It's crazy but mine doesn't work even with the above changes applied. Only hum comes out (sounding same like when touching an unplugged input jack). Please, can you recheck the layout once more? My ICs and JFET voltages are as follows:

Hi OzzySome voltages are not good. 5 steps should only be used LM324 parallel with the 4013, not on the first above!How you apply?I'll give you my voltages but you must be a mistake somewhere.Also I see if your input voltage is above 9v,and that after passing through the diode D4.This shows that you do not have stabilized voltage 9v.My power suplie is exactly 9v after diode D4 8.39v in all integrated circuits.Although I think that this is not a real problem at your place but this is the basic thing.Application L7809 in power suplies.The following message sending these voltages.Check once more,do not give up man!

Hi Ozzy, i was just starting to measure my voltages when i discovered that after the pedal is on for a bit my voltages right across the pedal drop.Plugged it in and i lose the octave effect. It seems i may have an additional problem with my build. If i can figure it out and get it working properly i'll post the voltages for you.

Ozzy,yes, I used the schedule which is set Alex,with 5-step changes.The first schedule.It is now taken care of and you can see it.I will try it by your voltages to find something.You check under the scheme on the blog, now with the changes.Look at my voltages,Look at my voltages,where there is disagreement regarding check components.Lm324 upper one,pin 14 must be the same voltage as pin 13.Chek capacitors 22n which connects them.The same voltage must be on pin 6.Further,Lm324 parallel to 4013,the quad-opamp output pin1,7,8,14,must be a voltage.Check it out and diodes D1 i D4.Fet transistor is eccentric.That's what you've got brum is proof your signal goes to ground.Monitors signal from the start and the end.That's all I can do this.I hope that you will succeed.

hello guys...i've just finish to build, but there's a tremendous volume loss, even with pot volume all turned up...i changer just one thing: i put 2n5458 instead of 2n5459 (hard to find)...could it be the problem? i've build the modern one, is it verified?thanx

Sorry mates. but were are Sw1-4 and Sw2-4 connected to? I made it, i didnt connect Sw2-4 and Sw1-4 nowhere and the signal passes through, every knob does something... but it isnt remotely close to octave effect :P (i meesed up somewere)

A number of people have asked me to do a build guide for one of these effects, but I noticed the other day that one of the guys here (timmy)...

Note

Not all these layouts are verified and some are put together from unverified schematics. So if you have good luck, or bad luck for that matter, then please let me know by dropping a comment in the topic. Thanks.

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